Field of the Invention
The present invention relates to a radiographic image capturing system, specifically, a radiographic image capturing system including a capturing stand for capturing a long image by one-shot exposure.
Description of Related Art
An example of the recently developed capturing stands for supporting radiographic image capturing devices (flat panel detectors) used for capturing radiographic images of relatively large areas of a patient, such as a full spine or a full leg, (i.e., a long image) is, for example, with reference to FIG. 20A, a capturing stand 100 including a holder 101 carrying multiple radiographic image capturing devices P1 to P3 aligned along the body axis A of a patient H (in the vertical direction in FIG. 20A) (for example, refer to Japanese Patent Application Laid-Open No. 2012-045159). The number of radiographic image capturing devices P to be loaded in the holder 101 is not limited to three.
Capturing of a long image using such a capturing stand can be carried out by positioning the patient H and the holder 101 (i.e., the radiographic image capturing devices P1 to P3) and irradiating the multiple radiographic image capturing devices P1 to P3 once via the subject (i.e., patient H) with radiation from the radiation irradiator 102 (i.e., one-shot exposure).
Although not illustrated, traditional capturing of a long image is carried out by irradiating a single radiographic image capturing device P loaded in a holder with radiation multiple times from the radiation irradiator 102 while moving the radiographic image capturing devices P1 to P3 in the vertical direction. Unfortunately, the patient could move during movement of the radiographic image capturing device P together with the holder. Capturing a long image by one-shot exposure is advantageous in that such problem due to body movement does not occur.
As illustrated in FIG. 20A, capturing of a long image through a single exposure of the multiple radiographic image capturing devices loaded in the holder to radiation with a subject disposed in front of the radiographic image capturing devices is referred to as “capturing a long image by one-shot exposure.” In the layout of the multiple radiographic image capturing devices in the holder, the bottom radiographic image capturing device P is disposed closer to the radiation irradiator 102 compared to the top radiographic image capturing device P in the holder 101, as illustrated in FIG. 20A, or the multiple radiographic image capturing devices P are staggered in the holder 101 so as to be alternately adjacent to or remote from the radiation irradiator 102, as illustrated in FIG. 20B.
Besides the vertical capturing stand 100 that captures a long image by one-shot exposure of the patient H in an upright position, as illustrated in FIGS. 20A and 20B, a horizontal capturing stand, such as that illustrated in FIG. 21, may also be used to capture a long image by one-shot exposure with radiation emitted once from above a recumbent patient H on a top panel 103 disposed above a holder 101 carrying horizontally aligned radiographic image capturing devices P1 to P3.
With reference to FIGS. 20A, 20B, and 21, edges of the radiographic image capturing devices P1 to P3 loaded in the holder 101 of the capturing stand 100 for capturing a long image by one-shot exposure overlap in view from the radiation irradiator 102. Thus, the radiographic image capturing device P in front from the radiation irradiator 102 is projected on the image acquired by the radiographic image capturing device P in the back from the radiation irradiator 102.
Among the radiographic image capturing devices loaded in a holder in a capturing stand according to the present invention, the radiographic image capturing device close to the radiation irradiator is referred to as a front radiographic image capturing device, and the radiographic image capturing device remote from the radiation irradiator is referred to as a rear radiographic image capturing device, in the case of not only the holder being installed in the vertical capturing stand 100 illustrated in FIGS. 20A and 20B, but also the horizontal capturing stand 100 illustrated in FIG. 21. Thus, the front radiographic image capturing device P in the capturing stand 100 illustrated in FIG. 21 is the top radiographic image capturing device P close to the radiation irradiator 102, and the rear radiographic image capturing device P is the bottom radiographic image capturing device P remote from the radiation irradiator 102.
With reference to FIG. 22A, an image p1 acquired by the rear radiographic image capturing device P1 (see FIG. 20A) contains transverse streaky components CL caused by linear structures, such as the edges of the casing and/or inner structure of the front radiographic image capturing device P2, and structural components CS caused by the structures in the casing of the front radiographic image capturing device P.
With reference to FIG. 22B, an image p2 acquired by the rear radiographic image capturing device P2 contains streaky components CL caused by linear structures, such as the edges of the casing and/or inner structure of the front radiographic image capturing device P3, and structural components CS caused by the structures in the casing of the front radiographic image capturing device P3.
The streaky components CL do not necessarily have a width of one pixel and could have a width of several pixels to several tens of pixels. The streaky components CL and the structural components CS in the image p1 illustrated in FIGS. 22A and 22B are depicted to contain pixels having pixel values of 0 for simplicity. Actually, the pixels of the streaky components CL and the structural components CS do not have pixel values of 0 but pixel values smaller than the original values.
As described above, the image p1 acquired by the rear radiographic image capturing device P containing the streaky components CL and the structural components CS cannot be precisely aligned and combined with the image p2 acquired by the front radiographic image capturing device P. Thus, the images cannot be combined to generate a long image.